1. Field of the Invention
This invention relates to an optical fiber holder used in optical connectors or the like which join the individual optical fibers.
2. Description of the Related Art
To Join the individual optical fibers, a method has been hitherto employed in which an end of an optical fiber is brought into hold with a holder called a ferrule and the holder having the optical fiber is fitted to a connector or the like so that ends of optical fibers to be joined are precisely butted to each other and fixed. In such an instance, the optical fiber is required to be securely held so as not to be damaged and also not to come off, because even a little fault produced when the optical fiber is brought into hold with the holder may cause a break.
As methods for bringing ends of optical fibers into hold with holders, it has been proposed to use (1) a method in which the optical fiber is inserted into a cylindrical sleeve and fixed with an adhesive, (2) a method as disclosed in Japanese Patent Publication No. 5-48446 in which the optical fiber is inserted to a metal pipe or the like and is secured by mechanically clamping the metal pipe, (3) notches are made in a metal pipe at its one end in the axial direction to a certain extent, and the notched end is branched off (or made divergent or fishtail) to form an elastic tail portion, where the optical fiber is inserted to the metal pipe thus worked and thereafter the elastic tail portion is pressed to elastically clamp and fix the optical fiber, and (4) a method as disclosed in Japanese Patent Application Laid-open No. 63-18306, in which a plurality of metal tube members having circular cross sections are longitudinally provided around the optical fiber, and the optical fiber is fixed by holding these tube members in a compressed state by means of a holding member provided around the tube members.
However, in the case where the optical fiber is fixed with an adhesive as in the above (1), it takes time to pretreat the optical fiber and dry the adhesive, bringing about not only a poor productivity but also a possibility that the position of the optical fiber may turn aside before the adhesive solidifies.
In the method where the metal pipe is directly clamped as in the above (2), the optical fiber may be damaged, e,g., broken, if it is clamped with even a little to strong of a force, and on the other hand the optical fiber may come off if it is clamped with to weak of a force, causing the problem that the force of clamping must be strictly controlled.
In the method where the elastic tail portion formed in the metal pipe is utilized as in the above (3), the area at which the optical fiber is elastically held is very small to cause the problem that the materials for the holding portion and the precision of working must be strictly controlled.
In the method where the tube members having circular cross sections are used as in the above (4), the tube members are only in linear contact with the optical fiber, and hence no sufficient force of fixing can be obtained, causing the optical fiber to come off in some cases.